Cosmetics cold resistance testing is a low-temperature stability test that evaluates how finished cosmetic products and their packaging withstand sub-zero storage and transport conditions. By exposing samples to defined cold temperatures—typically −5°C to −15°C for 24 hours—followed by recovery at room temperature, manufacturers can verify that creams, lotions, cleansers, and other formulations retain their appearance, texture, and performance. This article explains the technical principles, sample types, testing methods, evaluation criteria, and typical applications of cold resistance testing in accordance with recognized standards such as ISO/TR 18811 and GB/T product standards.
Technical Overview
Cold resistance testing is an accelerated stability test in which a finished cosmetic product, in its final sales packaging, is exposed to a specified low temperature for a defined period—most commonly 24 hours—and then allowed to recover at room temperature before evaluation. The purpose of the test is to reveal physical instabilities that only appear under cold stress, such as phase separation, crystallization of dissolved actives, precipitation, abnormal thickening, gelation, and cracking or embrittlement of packaging materials.
Low temperature stresses cosmetic formulations in several ways. It increases the viscosity of aqueous and emulsion phases, reduces the solubility of humectants, surfactants, active ingredients, and preservatives, and changes the crystalline structure of waxes and butters in anhydrous products. In oil-in-water emulsions, partial freezing of the water phase can disrupt the interfacial film, causing droplet coalescence, creaming, or complete phase separation after thawing. Even if a product appears intact immediately after thawing, subtle changes in viscosity, spreadability, or preservative distribution may compromise quality and consumer safety.
Internationally, ISO/TR 18811 (Cosmetics — Guidelines for the stability testing of cosmetic products) recommends low-temperature storage at levels such as 5°C, −5°C to −10°C, and −15°C to −25°C as part of a comprehensive stability program. In the Chinese market, many national and industry product standards for cosmetics (GB/T and QB/T series, such as those covering skincare lotions, facial cleansers, shampoos, and hair conditioners) specify a mandatory cold resistance requirement, most commonly −5°C ± 2°C or −10°C ± 2°C for 24 hours, with stricter levels such as −15°C applied to certain water-in-oil emulsions and stick products. Cold resistance testing is normally performed alongside heat resistance testing (for example, 40°C to 48°C for 24 hours), centrifugal stability testing, and light stability testing to form a complete stability profile.
Testing Samples
Emulsion Products (Creams, Lotions, and Moisturizers)
Oil-in-water and water-in-oil emulsions are the most commonly tested category. These products are particularly sensitive to freezing because ice crystal formation in the water phase can break the emulsion. After cold exposure and recovery, samples are inspected for creaming, water exudation, coalescence, and loss of uniformity. Water-in-oil systems and products with high water content are generally tested at more severe temperatures.
Aqueous Products (Toners, Essences, Shampoos, and Cleansers)
Water-based toners, essences, facial cleansers, shampoos, and body washes are evaluated for freezing behavior, sedimentation or precipitation of dissolved ingredients, turbidity, and restorability after shaking. Surfactant-based cleansing products may exhibit salt precipitation or haziness at low temperatures, especially when electrolyte thickeners are used.
Anhydrous Products (Lipsticks, Balms, and Solid Oils)
Lipsticks, lip balms, and solid balm products are tested for surface sweating, blooming, cracking, and changes in break strength or pay-off after cold exposure. These products often contain waxes and butters whose crystal structure can reorganize at low temperature, producing white bloom or a rough, grainy texture.
Gel Products (Hair Gels, Aloe Gels, and Peel-Off Masks)
Carbomer- and natural gum-based gels are highly susceptible to syneresis (water separation), loss of clarity, and permanent structure breakdown after a freeze–thaw event. Cold resistance testing verifies that the gel network recovers its original texture and transparency.
Special Formats (Sunscreen Sprays, Sheet Masks, and Aerosol Products)
Pressurized and packaged formats require additional attention to packaging performance at low temperature, including valve and pump actuation, can integrity, seal performance, and sachet or pouch leakage. Sheet masks are evaluated for essence separation and fabric rewetting after recovery.
Testing Items
Depending on the product standard and the intended market, the cold resistance test evaluates one or more of the following characteristics after the recovery period:
- Appearance: color, luster, uniformity, and visual comparison against a room-temperature control sample
- Odor: absence of off-odors or changes in fragrance profile after cold exposure and recovery
- Phase stability: no stratification, creaming, water exudation, or oil separation
- Crystallization and precipitation: no grittiness, crystals, sediment, or haze that does not redisperse
- Restorability: the product returns to its original state at room temperature, with or without gentle shaking as instructed on the label
- Viscosity and flow properties: measured with a viscometer and compared against the product specification and control sample
- pH: measured after recovery to confirm no drift beyond the specified range
- Centrifugal stability: often combined as a complementary check to reveal borderline emulsion instability
- Packaging integrity: no cracking, deformation, leakage, label peeling, or pump and valve malfunction caused by low temperature
- Functional performance: spreadability, foaming, pay-off, or application behavior consistent with pre-test values
Testing Methods
Standard Condition Method (Single Low-Temperature Exposure)
The most widely used procedure follows the format specified in Chinese GB/T and QB/T cosmetics product standards. Samples are kept in their original sales packaging and placed in a temperature-controlled refrigerator or climatic chamber set to the specified temperature—commonly −5°C ± 2°C, −10°C ± 2°C, or −15°C ± 2°C depending on the product category. After 24 hours of continuous exposure, the samples are removed and allowed to recover at room temperature (typically 23°C to 25°C) until thermally equilibrated. The recovered samples are then inspected side by side against control units stored at room temperature, and the results are recorded photographically and in the test report.
Graded Low-Temperature Screening (ISO/TR 18811 Approach)
For research and development purposes, a graded exposure scheme provides more informative stability data. Duplicate samples are stored simultaneously at several temperature levels—for example, 5°C, −5°C to −10°C, and −15°C to −25°C—for periods ranging from one week to several months. Samples are withdrawn at intervals and evaluated for appearance, viscosity, pH, and microbiological or preservative performance. This approach identifies the lowest temperature at which the formulation remains stable and supports packaging and labeling decisions for cold-climate markets.
Freeze–Thaw Cycle Testing
Freeze–thaw cycling subjects samples to repeated alternating exposures, for example 24 hours at −10°C followed by 24 hours at room temperature or 40°C, repeated for three to six cycles. This method simulates the temperature fluctuations encountered during winter logistics, cross-border e-commerce shipping, and unheated warehouse storage, and is more aggressive than a single cold hold. It is particularly valuable for emulsions and gels destined for cold regions.
Equipment and Procedure Requirements
- Use a calibrated low-temperature incubator or refrigerated chamber capable of maintaining the set point within ±2°C, with continuous temperature recording
- Prepare at least two sample units per condition, plus a room-temperature control, all from the same production batch
- Position samples so that air can circulate freely around the packaging, and avoid contact with chamber walls
- Allow a defined recovery period at room temperature before evaluation, and perform visual inspection under standardized lighting
- Measure pH, viscosity, and other parameters using calibrated instruments and compare against both the specification and the control sample
Acceptance Criteria
Typical acceptance criteria, consistent with common product standards, require that after recovery to room temperature the sample shows no stratification, no water separation, no crystallization or precipitation, no discoloration, and no abnormal odor; the product must return to its original homogeneous state and remain within the specified ranges for pH and viscosity. Any permanent change that cannot be restored by gentle shaking, or any packaging failure such as cracking or leakage, constitutes a failed result. Testing may be performed in-house or by accredited third-party laboratories using validated equipment and documented procedures.
Applications
Cold resistance testing supports the cosmetics industry at multiple stages of the product life cycle:
- Formulation development: screening candidate formulas for low-temperature robustness before scale-up, and guiding selection of humectants, emulsifiers, and freezing-point depressants
- Quality control: routine release testing of production batches against the cold resistance clause of the applicable GB/T or QB/T product standard for the Chinese market
- Regulatory compliance: generating stability data for regulatory dossiers and product safety assessments that require evidence of physical stability under foreseeable storage conditions
- Cold-chain logistics validation: demonstrating that products survive winter distribution, unheated warehouses, air cargo holds, and last-mile delivery to cold regions
- Claim substantiation: supporting labeling claims such as suitability for cold climates or stability across a wide temperature range
- Packaging development: verifying that bottles, jars, sachets, pumps, and aerosol valves maintain integrity and functionality at sub-zero temperatures
- Shelf-life assessment: combining cold resistance data with heat, light, and centrifugal stability results to establish a defensible expiry period
FAQ
What temperature is used for the cosmetics cold resistance test?
Common Chinese product standards specify −5°C ± 2°C or −10°C ± 2°C for 24 hours, while certain water-in-oil emulsions and stick products are tested at −15°C ± 2°C. For R&D screening, ISO/TR 18811 recommends testing at multiple levels, including 5°C, −5°C to −10°C, and −15°C to −25°C, to determine the lowest stable temperature.
How long are samples held at the low temperature?
The standard exposure period is 24 hours of continuous storage, after which samples are returned to room temperature and allowed to equilibrate before evaluation. Extended studies may hold samples for several days or weeks, and freeze–thaw protocols repeat the cycle three to six times.
What is the pass criterion for the test?
A sample passes if, after recovery to room temperature, it shows no separation, stratification, crystallization, precipitation, discoloration, or off-odor; returns to its original homogeneous state; remains within the specified pH and viscosity ranges; and shows no packaging defects such as cracking or leakage.
Is cold resistance testing mandatory for cosmetics sold in China?
Many GB/T and QB/T product standards for specific cosmetic categories include a cold resistance requirement as part of product quality evaluation, and stability evidence is expected in the overall product safety assessment. Manufacturers should verify the clause applicable to their product category and market.
How does cold resistance testing differ from freeze–thaw cycle testing?
Cold resistance testing is a single, continuous low-temperature exposure followed by one recovery, whereas freeze–thaw cycling alternates between cold and warm conditions several times. Cycling is more aggressive and better simulates real-world temperature fluctuations during transport and storage, so it is often used for products distributed in cold climates.
Can cold resistance testing predict shelf life?
On its own it cannot, but it is an essential component of a stability program. When combined with heat resistance testing, centrifugal testing, light exposure studies, and long-term room-temperature storage, cold resistance data supports a scientifically justified shelf-life determination.
Which products are most likely to fail the test?
High-water-content gels and emulsions, formulas in which active ingredients are near their solubility limit, electrolyte-thickened surfactant systems, and wax-based sticks with poorly optimized crystallization behavior carry the highest risk of cold-induced instability. Early screening during formulation can identify and correct these weaknesses before market launch.